Disaccharides are sugars formed when two monosaccharides (simple sugars) are linked by glycosidic linkage. Like the monosaccharides, the disaccharides are soluble in water. Three common examples are sucrose, lactose and maltose.
Disaccharides are one of four chemical groups of carbohydrates (monosaccharides, disaccharides, oligosaccharides and polysaccharides). The most common types of disaccharides-sucrose, lactose and maltose-have twelve carbon atoms, with the general formula C12H22O11.
Examples of disaccharides
Saccharose
Sucrose, commonly known as table sugar in its refined form, is a disaccharide found in many plants. It consists of the monosaccharides glucose and fructose.
In the form of sugar, sucrose is a very important component of the human diet as a sweetener. Sugar was first extracted and purified from sugarcane in India in the 8th century BC.
In fact, the word candy takes its name in part from the word"khanda", which was a name for sugar crystals in Sanskrit.
H O and in day, about 175 metric tons of sugar are produced every year. People with congenital sucrase-isomaltase deficiency are intolerant to sucrose and can not digest it well because they lack the enzyme sucrose-isomaltase.
A person who is intolerant to sucrose should limit sucrose as much as possible, and should take supplements or medications.
Maltose
Also known as malt sugar, it is formed from two molecules of glucose. Malt is formed when the grains soften and grow in water, and is a component of beer, starchy foods such as cereals, pasta and potatoes, and many processed foods.
In plants, maltose is formed when starch is broken down for food. It is used to germinate seeds.
Lactose
Lactose, or milk sugar, is composed of galactose and glucose. Mammalian milk is high in lactose and provides nutrients for babies.
Most mammals can only digest lactose as infants, and they lose this ability as they mature. In fact, humans who are able to digest dairy products in adulthood actually have a mutation that allows them to do so.
That's why so many people are lactose intolerant; Humans, like other mammals, did not have the ability to digest lactose in infancy until this mutation was present in certain populations about 10,000 years ago.
Today, the number of people who are lactose intolerant varies widely among populations, ranging from 10% in northern Europe to 95% in parts of Africa and Asia. Traditional diets from different cultures reflect this in the amount of dairy products consumed.
Trehalosa
Trehalose is also made up of two glucose molecules like maltose, but the molecules are linked differently. It is found in certain plants, fungi and animals such as shrimp and insects.
The blood sugar of many insects, such as bees, grasshoppers and butterflies, is composed of trehalose. They use it as an efficient storage molecule that provides fast energy for flight when it breaks down.
Chitobiosa
It consists of two linked glucosamine molecules. Structurally, it is very similar to cellobiose, except that it has an N-acetylamino group where cellobiose has a hydroxyl group.
It is found in some bacteria, and is used in biochemical research in order to study enzymatic activity.
It is also found in chitin, which forms walls of fungi, exoskeletons of insects, arthropods and crustaceans, and is also found in fish and cephalopods such as octopus and squid.
Celobiosa (Glucose + glucose)
Cellobiose is a product of hydrolysis of cellulose or materials rich in cellulose, such as paper or cotton. It is formed by binding two molecules of beta-glucose by a β-bond (1 → 4)
Lactulose (Galactose + fructose)
Lactulose is a synthetic (artificial) sugar that is not absorbed by the body but breaks down in the colon into products that absorb water in the colon, which softens the stool. Its primary use is to treat constipation.
It is also used to reduce blood ammonia levels in people with liver disease, as lactulose absorbs ammonia in the colon (removing it from the body).
Isomaltosa (Glucose + Glucose Isomaltase)
Produced during the digestion of starch (bread, potatoes, rice), or artificially produced.
Isomaltulose (Glucose + Fructose Isomaltase)
Sugar cane syrup, and honey is also produced artificially.
Trehalosa
Trehalulose is an artificial sugar, a disaccharide composed of glucose and fructose linked by an alpha (1-1) glycosidic bond.
It occurs during the production of isomaltulose from sucrose. In the lining of the small intestine, the enzyme isomalase breaks down into trehalulose to glucose and fructose, which are then absorbed into the small intestine. Trehalulose has a low potency to cause tooth decay.
Chitobiosa
It is the disaccharide repeat unit in chitin, which differs from cellobiose only in the presence of an N-acetylamino group on carbon-2 instead of the hydroxyl group. However, the non-acetylated form is often also called chytobiose.
Lactitol
It is a crystalline alcohol C 12 H 24 O 11 obtained by hydrogenation of lactose. It is an analog disaccharide of lactulose, used as sweetener. It is also laxative and is used to treat constipation.
Turanosa
An organic disaccharide reducing compound that can be used as a carbon source by bacteria and fungi.
Melibiosa
A disaccharide sugar (C12H22O11) formed by partial hydrolysis of raffinose.
Xylobiosa
A disaccharide consisting of two xylose residues.
Soforosa
A disaccharide present in a sophorolipid.
Gentiobiosa
Gentiobiose is a disaccharide consisting of two D-glucose units linked by a β-type glycosidic bond (1 → 6). Gentiobiose has many isomers which differ by the nature of the glycosidic bond connecting the two glucose units.
Leucous
It is a glycosylfructose consisting of an α-D-glucopyranosyl residue bound to D-fructopyranose via a bond (1 → 5). An isomer of sucrose.
Rutinous
It is a disaccharide present in glycosides.
Caroliniaside A
Oligosaccharides containing two units of monosaccharides linked by a glycosidic bond.
References
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